(502) 
was traced graphically on the drawing table. These profiles are at known inter- 
vals. (In our case it was 50 m). 
The dendrometric volume is then obtained by multiplying the area of each 
profile by the interval and by an appropriate coefficient experimentally deter- 
mined. This coefficient changes with the specimen of wood, the height, the den- 
sity and age of the tree, etc. 
(b) In case of different age wood, Dr. Cosema thought and developed a 
special procedure consisting of testing some small definite surfaces for each 
specimen of wood, chosen in such a way that they have the general and regular 
features of the considered zone. 
The form of these surfaces may be round, and this is the better form because 
on a same area corresponds a minimum perimeter and therefore the less number 
of trees, but generally the surfaces are square or rectangular of which the vertex 
coincides with well determined ground points. Sometimes it would be advisable 
to use long and narrow test surfaces especially when the wood had a uniform 
density. 
Then with the Stereocartograph we plot the tree foliage included in the 
surface and we measure the height of the trees. 
The work goes on now with the measurements of the foliage diameter (i.e. 
the area covered by each tree) and regrouping the trees of same heights so as to 
determine the ratio between the area and the height from which we found the 
reduction coefficient F» and the volume of the tested area. The total volume of 
the surface on the whole is therefore given by a simple formula in which the 
wood volume of the tested area is multiplied by the ratio between the total 
surface and the surface of the tested area. 
After checking by direct measuration we have found the following errors: 
+ 0.25 m in height 
+ 5 to 8% in dendrometric results with reference to the classical methods. 
In order to facilitate the statistical research concerning the relation among 
the single parts of the trees so as to eliminate at the most the ground surveys, 
we think that it would be useful to take some tilted views in clear spaces of 
wood where the single tree is shown from top to bottom so as to be able to study 
the dimensions by means of the stereoscopical plotting. 
We hope that this first systematic experiment will be followed by a more 
extended and continuous research so that the firms who are interested in this 
special type of work may develop the most suitable instruments and train 
appropriately the technicians. 
The unit cost already reduced with respect to the previous ones will then 
still become lower. 
THE THEORETICAL ACCURACY IN THE STEREOPHOTO- 
GRAMMETRICAL SURVEY OF SHELL AND BOMB 
TRAJECTORIES WITH THE CLASSICAL METHODS 
by 
Commander Luigi Ronca. 
In 1952 Omi Nistri have completed a new model of their equipment for 
classical stereophotogrammetry made of a stereocomparator model B and 
  
  
  
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